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Mbauer
08-06-2008, 09:16 AM
Hi,

I'm using Lightwave 8.3 on a Mac.

I have a scene where the camera is looking down on a map. As the camera pans across the map a whole bunch of thumbtacks fall from above the camera (off screen) and then stick in the map. Pretty simple and straightforward. The problem I'm having is that the shadows from the tacks are visible on the map while they are above the camera waiting to fall and I don't want them to be visible until they start falling. I don't want to go through and put an animated dissolve on every single tack (there's a bunch). So my solution was to put a plane above the camera (off screen) but below the tacks, thinking this would receive and block the shadows until after the tacks passed through the plane. But that doesn't work and I can't figure out why. I have the plane set to receive shadows, but not cast them. I tried a double sided plane and I tried a plane with volume, neither worked. The tack's shadows seem to just disregard the plane and go right through to the map. Does any of that make sense? Can anyone tell me what I'm missing?

Thanks

Wrap
08-06-2008, 09:47 AM
You could try lighting with spot lights below the origin of the tacks so that the tacks only start to cast shadow as they fall through the light?

toby
08-10-2008, 09:27 PM
Your shadow-blocking trick doesn't work because as long as the light is hitting the tacks and the map is receiving shadows, it will show them. In other words, you can't block shadows, only the light that casts them.

Easy - angle the light so that the shadows are off-screen, and they'll come in from the side as the tacks come down.

If you can't move the light, render the shadows separately and fade them in, in a compositing program. Or use an area light so that the shadows are so soft they're not noticeable, they'll fade themselves in as the tacks get closer.

Mbauer
08-13-2008, 02:10 PM
Your shadow-blocking trick doesn't work because as long as the light is hitting the tacks and the map is receiving shadows, it will show them. In other words, you can't block shadows, only the light that casts them.

hmmm, it seems like it should work this way. Why would you want a shadow to pass all the way through an object? I'll have to put that in the feature requests.

Anyways, thanks for the help, both of your solutions worked for me.:thumbsup:

MB